CVE-2009-0238: Microsoft Office Remote Code Execution

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Microsoft Office. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-04-14, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-04-28; treat that as the outer limit, not the target.
• EPSS 42.9%, percentile 99: FIRST’s model estimates a 42.9% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
• Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.

What it is

Microsoft Office Excel 2000 SP3, 2002 SP3, 2003 SP3, and 2007 SP1; Excel Viewer 2003 Gold and SP3; Excel Viewer; Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1; and Excel in Microsoft Office 2004 and 2008 for Mac allow remote attackers to execute arbitrary code via a crafted Excel document that triggers an access attempt on an invalid object, as exploited in the wild in February 2009 by Trojan.Mdropper.AC.

CISA’s summary

Microsoft Office Excel contains a remote code execution vulnerability that could allow an attacker to take complete control of an affected system if a user opens a specially crafted Excel file that includes a malformed object.

Weakness type: CWE-94.

Product: Microsoft Office · Assigned by: microsoft · Published: 2009-02-25

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: required (a user must click/open something)
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2026-04-14; federal due date 2026-04-28. Known ransomware use: Unknown.
• CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
• CISA SSVC assessment: exploitation active, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 42.94% probability of exploitation activity in the next 30 days; percentile 99.

Timeline

• 2009-02-25 — CVE record published by microsoft
• 2026-04-14 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-04-15 — CVE record last updated
• 2026-04-28 — CISA remediation deadline for US federal agencies

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. MS09-009 docs.microsoft.com
2. Listed in CISA KEV notes (learn.microsoft.com) learn.microsoft.com

Vulnerability records

1. CVE.org record CVE-2009-0238 cve.org
2. NVD entry CVE-2009-0238 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov

Other references from the CVE record and advisory

1. microsoft.com microsoft.com
2. ADV-2009-1023 vupen.com
3. ms-excel-unspecified-code-execution(48875) exchange.xforce.ibmcloud.com
4. TA09-104A us-cert.gov
5. 33870 securityfocus.com
6. symantec.com symantec.com
7. oval:org.mitre.oval:def:5968 oval.cisecurity.org
8. isc.sans.org isc.sans.org
9. 1021744 securitytracker.com
10. blogs.zdnet.com blogs.zdnet.com

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